Investigation of locally available coffee residue as effective adsorbent for dye polluted water treatments

Abstract

The coffee residues were used as a low-cost and effective adsorbent for the removal of methyl red from aqueous solution. The experiments were performed using operating parameters including initial dye concentration, contact time, solution pH, and adsorbent dosage under batch adsorption technique. The maximum methyl red removal (96.8%) was obtained at pH (2.0), contact time (20 min), initial dye concentration (10 mg/L), and adsorbent dose (0.5 g). The operating parameters such as initial dye concentration, contact time, pH, kinetic study, and adsorbent dosage were conducted; and the adsorption capacities were characterized by using the UV-Visible spectroscopy. The coffee residue before and after adsorption of methyl red was characterized by Fourier transform infrared spectroscopy. The results demonstrated that the coffee residues are very effective, simple, and inexpensive adsorbent in the removal of methyl red from aqueous solution because of its considerable adsorption capacity and abundance. The adsorption isotherms for Langmuir and Freundlich models were determined using the adsorption data. It was found that Freundlich isotherms described very well with the adsorption behavior of methyl red on coffee residue and followed the pseudo-second-order kinetic model.